Effect of the Crystallization Process and Solid State Storage on the Physico-Chemical Properties of Scale-up Lots of CI-936

N-(2,2-diphenylethyl)adenosine, designated as CI-936, is a novel, orally active antipsychotic agent. Depending on the manufacturing process, the drug substance exists in more than one crystalline form. Three lots of the drug were characterized by thermal analysis, scanning electron microscopy, X-ray diffraction, and dissolution. Two of these lots were found to be crystalline while the third was amorphous. The physical properties of the crystalline forms appear to change during storage under ambient conditions. The amorphous form, inspite of being in a high energy state, was not affected by storage. The absolute bioavailability of the amorphous form in dogs is more than 90%. In contrast, the other two crystalline lots demonstrated lower and unpredictable oral absorption profiles.